g_get_application_name ()

const gchar*        g_get_application_name              (void);

Gets a human-readable name for the application, as set by g_set_application_name(). This name should be localized if possible, and is intended for display to the user. Contrast with g_get_prgname(), which gets a non-localized name. If g_set_application_name() has not been called, returns the result of g_get_prgname() (which may be NULL if g_set_prgname() has also not been called).

Since 2.2

g_set_application_name ()

void                g_set_application_name              (const gchar *application_name);

Sets a human-readable name for the application. This name should be localized if possible, and is intended for display to the user. Contrast with g_set_prgname(), which sets a non-localized name. g_set_prgname() will be called automatically by gtk_init(), but g_set_application_name() will not.

Note that for thread safety reasons, this function can only be called once.

The application name will be used in contexts such as error messages, or when displaying an application's name in the task list.

Since 2.2

g_get_prgname ()

gchar*              g_get_prgname                       (void);

Gets the name of the program. This name should not be localized, contrast with g_get_application_name(). (If you are using GDK or GTK+ the program name is set in gdk_init(), which is called by gtk_init(). The program name is found by taking the last component of argv[0].)

g_set_prgname ()

void                g_set_prgname                       (const gchar *prgname);

Sets the name of the program. This name should not be localized, contrast with g_set_application_name(). Note that for thread-safety reasons this function can only be called once.

g_getenv ()

const gchar*        g_getenv                            (const gchar *variable);

Returns the value of an environment variable. The name and value are in the GLib file name encoding. On UNIX, this means the actual bytes which might or might not be in some consistent character set and encoding. On Windows, it is in UTF-8. On Windows, in case the environment variable's value contains references to other environment variables, they are expanded.

g_setenv ()

gboolean            g_setenv                            (const gchar *variable,
                                                         const gchar *value,
                                                         gboolean overwrite);

Sets an environment variable. Both the variable's name and value should be in the GLib file name encoding. On UNIX, this means that they can be any sequence of bytes. On Windows, they should be in UTF-8.

Note that on some systems, when variables are overwritten, the memory used for the previous variables and its value isn't reclaimed.

Since 2.4

g_unsetenv ()

void                g_unsetenv                          (const gchar *variable);

Removes an environment variable from the environment.

Note that on some systems, when variables are overwritten, the memory used for the previous variables and its value isn't reclaimed. Furthermore, this function can't be guaranteed to operate in a threadsafe way.

Since 2.4

g_listenv ()

gchar**             g_listenv                           (void);

Gets the names of all variables set in the environment.

Since 2.8

g_get_user_name ()

const gchar*        g_get_user_name                     (void);

Gets the user name of the current user. The encoding of the returned string is system-defined. On UNIX, it might be the preferred file name encoding, or something else, and there is no guarantee that it is even consistent on a machine. On Windows, it is always UTF-8.

g_get_real_name ()

const gchar*        g_get_real_name                     (void);

Gets the real name of the user. This usually comes from the user's entry in the passwd file. The encoding of the returned string is system-defined. (On Windows, it is, however, always UTF-8.) If the real user name cannot be determined, the string "Unknown" is returned.

g_get_user_cache_dir ()

const gchar*        g_get_user_cache_dir                (void);

Returns a base directory in which to store non-essential, cached data specific to particular user.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification

Since 2.6

g_get_user_data_dir ()

const gchar*        g_get_user_data_dir                 (void);

Returns a base directory in which to access application data such as icons that is customized for a particular user.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification

Since 2.6

g_get_user_config_dir ()

const gchar*        g_get_user_config_dir               (void);

Returns a base directory in which to store user-specific application configuration information such as user preferences and settings.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification

Since 2.6

enum GUserDirectory

typedef enum {
  G_USER_DIRECTORY_DESKTOP,
  G_USER_DIRECTORY_DOCUMENTS,
  G_USER_DIRECTORY_DOWNLOAD,
  G_USER_DIRECTORY_MUSIC,
  G_USER_DIRECTORY_PICTURES,
  G_USER_DIRECTORY_PUBLIC_SHARE,
  G_USER_DIRECTORY_TEMPLATES,
  G_USER_DIRECTORY_VIDEOS,

  G_USER_N_DIRECTORIES
} GUserDirectory;

These are logical ids for special directories which are defined depending on the platform used. You should use g_get_user_special_dir() to retrieve the full path associated to the logical id.

The GUserDirectory enumeration can be extended at later date. Not every platform has a directory for every logical id in this enumeration.

Since 2.14

g_get_user_special_dir ()

const gchar*        g_get_user_special_dir              (GUserDirectory directory);

Returns the full path of a special directory using its logical id.

On Unix this is done using the XDG special user directories. For compatibility with existing practise, G_USER_DIRECTORY_DESKTOP falls back to $HOME/Desktop when XDG special user directories have not been set up.

Depending on the platform, the user might be able to change the path of the special directory without requiring the session to restart; GLib will not reflect any change once the special directories are loaded.

Since 2.14

g_get_system_data_dirs ()

const gchar* const * g_get_system_data_dirs             (void);

Returns an ordered list of base directories in which to access system-wide application data.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification

On Windows the first elements in the list are the Application Data and Documents folders for All Users. (These can be determined only on Windows 2000 or later and are not present in the list on other Windows versions.) See documentation for CSIDL_COMMON_APPDATA and CSIDL_COMMON_DOCUMENTS.

Then follows the "share" subfolder in the installation folder for the package containing the DLL that calls this function, if it can be determined.

Finally the list contains the "share" subfolder in the installation folder for GLib, and in the installation folder for the package the application's .exe file belongs to.

The installation folders above are determined by looking up the folder where the module (DLL or EXE) in question is located. If the folder's name is "bin", its parent is used, otherwise the folder itself.

Note that on Windows the returned list can vary depending on where this function is called.

Since 2.6

g_get_system_config_dirs ()

const gchar* const * g_get_system_config_dirs           (void);

Returns an ordered list of base directories in which to access system-wide configuration information.

On UNIX platforms this is determined using the mechanisms described in the XDG Base Directory Specification

Since 2.6

g_reload_user_special_dirs_cache ()

void                g_reload_user_special_dirs_cache    (void);

Resets the cache used for g_get_user_special_dir(), so that the latest on-disk version is used. Call this only if you just changed the data on disk yourself.

Due to threadsafety issues this may cause leaking of strings that were previously returned from g_get_user_special_dir() that can't be freed. We ensure to only leak the data for the directories that actually changed value though.

Since 2.22

g_get_host_name ()

const gchar*        g_get_host_name                     (void);

Return a name for the machine.

The returned name is not necessarily a fully-qualified domain name, or even present in DNS or some other name service at all. It need not even be unique on your local network or site, but usually it is. Callers should not rely on the return value having any specific properties like uniqueness for security purposes. Even if the name of the machine is changed while an application is running, the return value from this function does not change. The returned string is owned by GLib and should not be modified or freed. If no name can be determined, a default fixed string "localhost" is returned.

Since 2.8

g_get_home_dir ()

const gchar*        g_get_home_dir                      (void);

Gets the current user's home directory as defined in the password database.

Note that in contrast to traditional UNIX tools, this function prefers passwd entries over the HOME environment variable.

One of the reasons for this decision is that applications in many cases need special handling to deal with the case where HOME is

Since applications are in general not written to deal with these situations it was considered better to make g_get_home_dir() not pay attention to HOME and to return the real home directory for the user. If applications want to pay attention to HOME, they can do:

1
2
3

const char *homedir = g_getenv ("HOME");
 if (!homedir)
    homedir = g_get_home_dir ();

g_get_tmp_dir ()

const gchar*        g_get_tmp_dir                       (void);

Gets the directory to use for temporary files. This is found from inspecting the environment variables TMPDIR, TMP, and TEMP in that order. If none of those are defined "/tmp" is returned on UNIX and "C:\" on Windows. The encoding of the returned string is system-defined. On Windows, it is always UTF-8. The return value is never NULL.

g_get_current_dir ()

gchar*              g_get_current_dir                   (void);

Gets the current directory. The returned string should be freed when no longer needed. The encoding of the returned string is system defined. On Windows, it is always UTF-8.

g_basename ()

const gchar*        g_basename                          (const gchar *file_name);

Gets the name of the file without any leading directory components. It returns a pointer into the given file name string.

g_dirname

#define             g_dirname

This function is deprecated and will be removed in the next major release of GLib. Use g_path_get_dirname() instead.

Gets the directory components of a file name. If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

g_path_is_absolute ()

gboolean            g_path_is_absolute                  (const gchar *file_name);

Returns TRUE if the given file_name is an absolute file name, i.e. it contains a full path from the root directory such as "/usr/local" on UNIX or "C:\windows" on Windows systems.

g_path_skip_root ()

const gchar*        g_path_skip_root                    (const gchar *file_name);

Returns a pointer into file_name after the root component, i.e. after the "/" in UNIX or "C:\" under Windows. If file_name is not an absolute path it returns NULL.

g_path_get_basename ()

gchar*              g_path_get_basename                 (const gchar *file_name);

Gets the last component of the filename. If file_name ends with a directory separator it gets the component before the last slash. If file_name consists only of directory separators (and on Windows, possibly a drive letter), a single separator is returned. If file_name is empty, it gets ".".

g_path_get_dirname ()

gchar*              g_path_get_dirname                  (const gchar *file_name);

Gets the directory components of a file name. If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

g_build_filename ()

gchar *             g_build_filename                    (const gchar *first_element,
                                                         ...);

Creates a filename from a series of elements using the correct separator for filenames.

On Unix, this function behaves identically to g_build_path (G_DIR_SEPARATOR_S, first_element, ....).

On Windows, it takes into account that either the backslash (\ or slash (/) can be used as separator in filenames, but otherwise behaves as on Unix. When file pathname separators need to be inserted, the one that last previously occurred in the parameters (reading from left to right) is used.

No attempt is made to force the resulting filename to be an absolute path. If the first element is a relative path, the result will be a relative path.

g_build_filenamev ()

gchar *             g_build_filenamev                   (gchar **args);

Behaves exactly like g_build_filename(), but takes the path elements as a string array, instead of varargs. This function is mainly meant for language bindings.

Since 2.8

g_build_path ()

gchar *             g_build_path                        (const gchar *separator,
                                                         const gchar *first_element,
                                                         ...);

Creates a path from a series of elements using separator as the separator between elements. At the boundary between two elements, any trailing occurrences of separator in the first element, or leading occurrences of separator in the second element are removed and exactly one copy of the separator is inserted.

Empty elements are ignored.

The number of leading copies of the separator on the result is the same as the number of leading copies of the separator on the first non-empty element.

The number of trailing copies of the separator on the result is the same as the number of trailing copies of the separator on the last non-empty element. (Determination of the number of trailing copies is done without stripping leading copies, so if the separator is ABA, ABABA has 1 trailing copy.)

However, if there is only a single non-empty element, and there are no characters in that element not part of the leading or trailing separators, then the result is exactly the original value of that element.

Other than for determination of the number of leading and trailing copies of the separator, elements consisting only of copies of the separator are ignored.

g_build_pathv ()

gchar *             g_build_pathv                       (const gchar *separator,
                                                         gchar **args);

Behaves exactly like g_build_path(), but takes the path elements as a string array, instead of varargs. This function is mainly meant for language bindings.

Since 2.8

g_format_size_for_display ()

char *              g_format_size_for_display           (goffset size);

Formats a size (for example the size of a file) into a human readable string. Sizes are rounded to the nearest size prefix (KB, MB, GB) and are displayed rounded to the nearest tenth. E.g. the file size 3292528 bytes will be converted into the string "3.1 MB".

The prefix units base is 1024 (i.e. 1 KB is 1024 bytes).

This string should be freed with g_free() when not needed any longer.

Since 2.16

g_find_program_in_path ()

gchar*              g_find_program_in_path              (const gchar *program);

Locates the first executable named program in the user's path, in the same way that execvp() would locate it. Returns an allocated string with the absolute path name, or NULL if the program is not found in the path. If program is already an absolute path, returns a copy of program if program exists and is executable, and NULL otherwise. On Windows, if program does not have a file type suffix, tries with the suffixes .exe, .cmd, .bat and .com, and the suffixes in the PATHEXT environment variable.

On Windows, it looks for the file in the same way as CreateProcess() would. This means first in the directory where the executing program was loaded from, then in the current directory, then in the Windows 32-bit system directory, then in the Windows directory, and finally in the directories in the PATH environment variable. If the program is found, the return value contains the full name including the type suffix.

g_bit_nth_lsf ()

gint                g_bit_nth_lsf                       (gulong mask,
                                                         gint nth_bit);

Find the position of the first bit set in mask, searching from (but not including) nth_bit upwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the 0th bit, set nth_bit to -1.

g_bit_nth_msf ()

gint                g_bit_nth_msf                       (gulong mask,
                                                         gint nth_bit);

Find the position of the first bit set in mask, searching from (but not including) nth_bit downwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the last bit, set nth_bit to -1 or GLIB_SIZEOF_LONG * 8.

g_bit_storage ()

guint               g_bit_storage                       (gulong number);

Gets the number of bits used to hold number, e.g. if number is 4, 3 bits are needed.

g_spaced_primes_closest ()

guint               g_spaced_primes_closest             (guint num);

Gets the smallest prime number from a built-in array of primes which is larger than num. This is used within GLib to calculate the optimum size of a GHashTable.

The built-in array of primes ranges from 11 to 13845163 such that each prime is approximately 1.5-2 times the previous prime.

g_atexit ()

void                g_atexit                            (GVoidFunc func);

Specifies a function to be called at normal program termination.

Since GLib 2.8.2, on Windows g_atexit() actually is a preprocessor macro that maps to a call to the atexit() function in the C library. This means that in case the code that calls g_atexit(), i.e. atexit(), is in a DLL, the function will be called when the DLL is detached from the program. This typically makes more sense than that the function is called when the GLib DLL is detached, which happened earlier when g_atexit() was a function in the GLib DLL.

The behaviour of atexit() in the context of dynamically loaded modules is not formally specified and varies wildly.

On POSIX systems, calling g_atexit() (or atexit()) in a dynamically loaded module which is unloaded before the program terminates might well cause a crash at program exit.

Some POSIX systems implement atexit() like Windows, and have each dynamically loaded module maintain an own atexit chain that is called when the module is unloaded.

On other POSIX systems, before a dynamically loaded module is unloaded, the registered atexit functions (if any) residing in that module are called, regardless where the code that registered them resided. This is presumably the most robust approach.

As can be seen from the above, for portability it's best to avoid calling g_atexit() (or atexit()) except in the main executable of a program.

g_parse_debug_string ()

guint               g_parse_debug_string                (const gchar *string,
                                                         const GDebugKey *keys,
                                                         guint nkeys);

Parses a string containing debugging options into a guint containing bit flags. This is used within GDK and GTK+ to parse the debug options passed on the command line or through environment variables.

If string is equal to "all", all flags are set. If string is equal to "help", all the available keys in keys are printed out to standard error.

GDebugKey

typedef struct {
  const gchar *key;
  guint	       value;
} GDebugKey;

Associates a string with a bit flag. Used in g_parse_debug_string().

GVoidFunc ()

void                (*GVoidFunc)                        (void);

Declares a type of function which takes no arguments and has no return value. It is used to specify the type function passed to g_atexit().

GFreeFunc ()

void                (*GFreeFunc)                        (gpointer data);

Declares a type of function which takes an arbitrary data pointer argument and has no return value. It is not currently used in GLib or GTK+.

g_qsort_with_data ()

void                g_qsort_with_data                   (gconstpointer pbase,
                                                         gint total_elems,
                                                         gsize size,
                                                         GCompareDataFunc compare_func,
                                                         gpointer user_data);

This is just like the standard C qsort() function, but the comparison routine accepts a user data argument.

g_nullify_pointer ()

void                g_nullify_pointer                   (gpointer *nullify_location);

Set the pointer at the specified location to NULL.